Messages in this thread | | | Date | Fri, 21 Nov 2008 17:40:41 +0100 | From | Joerg Roedel <> | Subject | Re: [PATCH 0/10] DMA-API debugging facility |
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On Fri, Nov 21, 2008 at 05:37:17PM +0100, Ingo Molnar wrote: > > * Joerg Roedel <joerg.roedel@amd.com> wrote: > > > Hi, > > > > this patchset introduces code to debug drivers usage of the DMA-API. > > Tests with hardware IOMMUs have shown several bugs in drivers > > regarding the usage of that API. Problems were found especially in > > network card drivers. > > > > These bugs often don't show up or have any negative impact if there > > is no hardware IOMMU in use in the system. But with an hardware > > IOMMU these bugs turn the hardware unusable or, in the worst case, > > cause data corruption on devices which are managed by other (good) > > drivers. > > > > With the code these patches introduce driver developers can find > > several bugs of misusing the DMA-API in their drivers. But be aware, > > it can not find all possible bugs. If it finds a problem it prints > > out messages like > > > > tg3 0000:08:04.0: PCI-DMA: device driver tries to free DMA memory it > > has not allocated [device address=0x000000042f0f3ae7] [size=48 > > bytes] > > > > Pid: 6285, comm: bash Not tainted 2.6.28-rc5-00176-g6ae6379-dirty #6 > > Call Trace: > > <IRQ> [<ffffffff80221276>] check_unmap+0x52/0x1ce > > [<ffffffff80221af0>] debug_unmap_single+0x61/0xa4 > > [<ffffffff8053d396>] skb_dma_unmap+0xf2/0x10c > > [<ffffffff8040a986>] tg3_poll+0xe8/0x822 > > [<ffffffff803abe2f>] mix_pool_bytes_extract+0x5c/0x155 > > [<ffffffff80540e42>] net_rx_action+0x9d/0x170 > > very nice! I like this approach - and have a few comments on some > details - will post them as a reply to the patchs.
Cool. Thank you.
Joerg
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